Suspension system for lawnmower

ABSTRACT

In a riding mower having a frame, a mower deck supported beneath the frame, a chair on said frame and a source of motive power also supported on said frame and including two hydraulic transaxles depending beneath the frame to each selectively rotate a drive wheel. The frame is supported on forward and rear wheel assemblies with a supporting wheel. The transaxles are supported beneath the frame and pivotally secured thereto by a flange captivating vibration pillows and proximate the driven wheel and an inner pivot rod secured to the frame by apertures in downwardly depending tabs.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/673,744, filed on Aug. 10, 2017 and titled “SUSPENSION SYSTEM FORLAWNMOWER”, which is a continuation-in-part of U.S. patent applicationSer. No. 14/735,640 (now U.S. Pat. No. 9,730,386), filed on Jun. 10,2015 and titled “SUSPENSION SYSTEM FOR LAWNMOWER”, which claims priorityto U.S. Provisional Patent Application No. 62/010,634, filed on Jun. 11,2014 and titled “SUSPENSION SYSTEM FOR LAWNMOWER”, each of which arehereby incorporated by reference in their entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not Applicable.

RESERVATION OF RIGHTS

A portion of the disclosure of this patent document contains materialwhich is subject to intellectual property rights such as but not limitedto copyright, trademark, and/or trade dress protection. The owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure as it appears in the Patent and TrademarkOffice patent files or records but otherwise reserves all rightswhatsoever.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates generally to riding mowers and, moreparticularly, to an improved suspension system for motive systems onsuch mowers or the like. Known art can be found in U.S. Class 280,subclass 124 and in other classes and subclasses.

2. Description of the Known Art

Those skilled in the art will appreciate that riding mowers have been astaple for maintaining residential yards, commercial lawns, golf coursesand highway rights of way for many years. They are seen moving alonggrass in many settings including grassy center dividers and along thesides of roads in rough, sometimes rocky terrain, and in all sorts ofattitudes from flat and level to severe side hills.

In many instances, an operator may be in the seat for hours, and evenwith a kidney belt, will suffer considerable discomfort and, in somecases, injury. Indeed, it is not inconceivable that the constantbouncing and jarring could cause an operator to lose control, resultingin damage to the operator and others.

The underlying purpose and function of the present invention is toprovide an element of relief to an operator and increased vehiclecontrol. The invention disclosed in U.S. Pat. No. 7,708,292 issued toFoster deals with these issues. While this invention works well for itsintended purpose, an improved system that places a hydrostatic axleproximate a drive wheel improves vehicle stability while also promotingoperator comfort.

Most of the other known riding mowers in use today have their wheelsaffixed directly to the frame of the mower. In the late '90s the selfproclaimed leader in the field, David Ferris, and others filed anapplication for a suspension system for riding mowers. The applicationclaims priority based on provisionals, at least one of which dates backto 1996, and was divided and one of those continuations-in-part issuedas Ferris et al. U.S. Pat. No. 6,460,318. The patent features a four barmechanism relatively common in automotive suspensions.

Known art which may be relevant to the present invention includes thefollowing patents with their abstracts, the teachings of which areincorporated by reference.

Gordon U.S. Pat. No. 6,170,242 is yet another patent assigned to FerrisIndustries and claims priority under a 1997 provisional, which is alsoclaimed under the earlier mentioned Ferris et al. patent. Gordon, likeFerris et al., features a four bar mechanism.

A very early patent featuring a rubber bumper between two elements in anautomotive structure is found in Hickman U.S. Pat. No. 3,737,174.

Several other patents offer variations on the same theme. See, forexample, Dunlap et al. U.S. Pat. No. 3,669,467, which has additionalbuffering devices, such as springs, leaf or coil, and shock absorbingdevices. Dunlap has a pair of cushions, but also uses a pair of rods 32and 34, which attach directly to the frame rail.

Krakowiak et al. U.S. Pat. No. 5,979,920, uses the simple bumper betweenthe frame rail and a leaf spring. This is a device which is common onmany of the earlier motor vehicles.

Merkle U.S. Pat. No. 4,310,717, uses what he refers to as an elastomericspring, again, between the frame rail and what he refers to as a websection which holds the axle upon which the wheel is connected. Itappears in the drawing that there may be a shock absorber in the middleof this assembly.

Bonzer et al. U.S. Pat. No. 4,559,669, employs a resilient buffer 19 fora caster assembly. Heitzman U.S. Pat. No. 5,899,470 uses a couple ofresilient buffers as part of a system for adjusting camber and caster.It is evident from these patents that using an elastomeric as a springor shock absorber is not new in the art. All of these references seek,to a greater or lesser extent, some modulation of the amplitude andfrequency of shock transmitted through a wheel of a vehicle, but areunsuited for a riding mower.

Also, commercially available equipment and components may be relevant,including hollow metal frames, shoe brushes and the like. Such equipmentmay be used in implementing an exemplary embodiment in accordance withthe present invention.

None of these references, either singly or in combination, disclose orsuggest the present invention. It is desirable to have a improvedlawnmower to address the perceived shortcomings of the known art.

While it is evident from past attempts that suspension systems forlawnmowers are desirable, the known art is limited in its teaching andutilization, and an improved system is needed to overcome theselimitations. An improved suspension system should provide a simple andefficient system for meeting the various needs of the users and thelike.

SUMMARY OF THE INVENTION

The present invention addresses the perceived needs in the known artdiscussed above. In this regard, the present invention substantiallyfulfills this need. The suspension system for lawnmower may beadvantageously used with zero-turn lawnmowers or others using transaxlescombined with hydraulic pumps for motive power and the like. Thetransaxles are dampened by at least one pillow interposed between theframe the wheel with each pillow being of a resilient material forabsorbing shock and vibration resulting from a wheel contactingirregularities in the terrain traversed thereby.

In one exemplary embodiment in accordance with the present invention animproved suspension system may be used with the rear axles to provide amotive source proximate the driven rear wheels and substantiallyisolated from the frame of the lawnmower to thereby dampen vibrationstransmitted to the operator as the vehicle traverses the ground.

The apparatus of the invention is capable of receiving additional,optional features which are not a part of the present invention. Forexample, a purchaser or user may specify an optional mulcher or baggeror the like for a lawnmower. Other optional features, some of which maybe illustrated herein, may or may not be included with apparatusincorporating the basic aspects of present invention.

In addition to providing the features and advantages referred to above,it is an object of the present invention to provide an improvedsuspension system for lawnmower.

Another object of the present invention is to provide a lawnmower with alowered center of gravity.

A basic object of the present invention is to provide a more stablelawnmower.

Yet another object of the present invention is to enhance user comfort.

A related object of the present invention is to provide a saferlawnmower.

These and other objects and advantages of the present invention, alongwith features of novelty appurtenant thereto, will appear or becomeapparent by reviewing the following detailed description of theinvention in conjunction with the appended drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the following drawings, which form a part of the specification andwhich are to be construed in conjunction therewith, and in which likereference numerals have been employed throughout wherever possible toindicate like parts in the various views:

FIG. 1 is a perspective view of a riding mower in accordance with anembodiment of the present invention;

FIG. 2 is a perspective view of the frame of the mower with the rearaxle assembly shown;

FIG. 3 is an enlarged perspective view of the encircled portion of FIG.2;

FIG. 4 is a top plan view of the frame;

FIG. 5 is a bottom plan view thereof;

FIG. 6 is an elevational view taken from the side with the opposite sidebeing a mirror image thereof;

FIG. 7 is an elevational view taken generally from the rear thereof;

FIG. 8 is an enlarged elevational view taken generally from the rearthereof and similar to FIG. 7 but showing movement; and,

FIG. 9 is an enlarged bottom plan view and similar to FIG. 5 but showingmovement and axes of rotation.

DETAILED DESCRIPTION OF THE INVENTION

The present invention addresses the perceived needs in the known artdiscussed above. In this regard, the present invention substantiallyfulfills this need. The improved suspension system for lawnmowerincludes a vibration damping system with transaxles that are attached tothe rear axle assemblies that also provide motive power thereto.

In one exemplary embodiment in accordance with the present invention andshown in FIGS. 1-9, an improved riding mower 11 is illustrated. Themower 11 has a frame 16 supported by a pair of forward wheel assemblies18 and rear wheel assemblies 72.

The frame 16 supports a mower deck 25, and a chair 27 is provided for adriver, with a pair of steering arms 29 within easy reach. A motorcompartment 32 rides on the frame and provides motive power to the mowerthrough right and left integrated hydrostatic transaxles 65 that driveright and left rear wheels 72 in response to operator manipulation ofcontrol handles 29.

One important feature of the present invention is the provision of themower 11 which has enhanced comfort and less fatigue for the driver, allof which increases the ability of the driver to control the mower, evenin unusual attitudes resulting from irregularities in the terrain, andover extended periods of operation, and particularly where terrainchanges are abrupt. In accomplishing its objectives, both forward andrear systems of vibration control are interposed between each of thesupporting wheel assemblies and the frame of the mower.

It is a feature of the present invention that a rear suspension systemis provided with vibration damping capability. Referring to FIGS. 2-10,the rear segment 62 of the frame 16 supports two spaced apart rear axletransaxles 65, which are mounted transverse to the longitudinal axis ofthe mower 11.

The frame supports downward flanges 66 that captivate a portion of eachtransaxle 65 on the sides of the mower 11. Each of the transaxles 65supports an outer driven wheel assembly 72 through an axle 73 and, inkeeping with the objectives of the invention, are articulated about apivot pin 74 (which may be a bolt and nut or other similar device) in aplane transverse to the plane of the transaxle housing. The pivot pin 74is secured in apertures 76 in tabs 78 depending from the frame 62.Companion apertures 78 align with the apertures 76 to receive the pivotpins 74 which then permit pivotal movement thereabout.

Movement of the wheel assemblies 72 is limited and vibration is dampenedby the provision of damping pillows 81 which are secured between thedownwardly depending frame flanges 60 on the forward and rear sides ofthe transaxles 65. The pivotal movement of each transaxle 65 is shown byarrow 68 with the axes of rotation indicated by lines 70, whichcorresponds to an accompanying compression or extension of the affectedpillows 81 (FIGS. 8 and 9).

Each pillow 81 is resilient and may be of any one of several durometersof rubber hardness, or may be of other suitable elastomeric materials,including elastic shells with a liquid or other compressible materialthere within, appropriate to the weight of the mower and the terrain tobe traversed. The pillows define a cushion between the wheel and theframe of the mower, thereby absorbing shock created by the wheel movingover the uneven terrain. Further, each wheel functions independently,i.e., independent of the frame, in order that it may respondindependently to variations in the terrain met by each individual wheel,which may be several feet removed from its companion wheel.

The pillows 81 are positioned between such flanges and a bolt 85 passesthrough the longitudinal axis of each pillow and is secured in aperturesin the aligned flanges to thereby hold the pillow between them. Thepillow is sized to abut the flanges above and beneath each, where it isheld in place by bolts, and the pillow is compressed by the rapid upwardmovement of a wheel assembly, thereby dampening that movement andinhibiting, or at least modulating, transmission of that movement to theframe of the mower. The rapid movement resulting from the traversing ofrocks and other debris is particularly well dampened. Moreover, if thewheel were to move downwardly, in a pot hole for example, it isinhibited from moving too rapidly or too far from its unstressedposition.

The apparatus of the invention is capable of receiving additional,optional features which are not a part of the present invention. Forexample, a purchaser or user may specify an optional railing or grabbars may be included to facilitate handling of the device duringdeployment. Other optional features, some of which may be illustratedherein, may or may not be included with apparatus incorporating thebasic aspects of present invention.

In describing a preferred embodiment of the invention illustrated in thedrawings, specific terminology has been used for the sake of clarity.However, the invention is not intended to be limited to the specificterms selected, and it is to be understood that each specific termincludes all technical equivalents which operate in a similar manner toaccomplish a similar purpose.

What is claimed is:
 1. A riding lawnmower system comprising: a frame; aright rear drive system comprising: a right integrated hydraulic driveunit comprising a right hydraulic pump, a right hydraulic motor and aright drive axle, the right drive axle configured to rotate about aright axle axis, and the right integrated hydraulic drive unit pivotallycoupled to the frame such that the right integrated hydraulic drive unitis configured to pivot about a right pivot axis oriented transverse tothe right axle axis; a right rear drive wheel coupled to the right driveaxle of the right integrated hydraulic drive unit, the right rear drivewheel configured to rotate about the right axle axis and to pivot aboutthe right pivot axis with the right integrated hydraulic drive unit; anda right resilient member configured to be compressed by pivoting of theright integrated hydraulic drive unit about the right pivot axis; and aleft rear drive system comprising: a left integrated hydraulic driveunit comprising a left hydraulic pump, a left hydraulic motor and a leftdrive axle, the left drive axle configured to rotate about a left axleaxis, and the left integrated hydraulic drive unit pivotally coupled tothe frame such that the left integrated hydraulic drive unit isconfigured to pivot about a left pivot axis oriented transverse to theleft axle axis, the left integrated hydraulic drive unit is separatefrom the right integrated hydraulic drive unit, the right integratedhydraulic drive unit is configured to pivot about the right pivot axisindependent of pivoting of the left integrated hydraulic drive unitabout the left pivot axis, and the left integrated hydraulic drive unitis configured to pivot about the left pivot axis independent of pivotingof the right integrated hydraulic drive unit about the right pivot axis;a left rear drive wheel coupled to the left drive axle of the leftintegrated hydraulic drive unit, the left rear drive wheel configured torotate about the left axle axis and to pivot about the left pivot axiswith the left integrated hydraulic drive unit; and a left resilientmember configured to be compressed by pivoting of the left integratedhydraulic drive unit about the left pivot axis.
 2. The system of claim1, wherein the right axle axis is oriented transverse to a longitudinalaxis of the riding lawnmower system, and the right pivot axis is offsetto a right side of the longitudinal axis of the riding lawnmower system,and wherein the left axle axis is oriented transverse to thelongitudinal axis of the riding lawnmower system, and the left pivotaxis is offset to a left side of the longitudinal axis of the ridinglawnmower system.
 3. The system of claim 1, wherein the right integratedhydraulic drive unit is configured to transmit motive power to rotatethe right rear drive wheel about the right axle axis, and wherein theleft integrated hydraulic drive unit is configured to transmit motivepower to rotate the left rear drive wheel about the left axle axis. 4.The system of claim 1, wherein pivoting of the right integratedhydraulic drive unit about the right pivot axis comprises the righthydraulic pump, the right hydraulic motor and the right drive axlepivoting together as a unit about the right pivot axis, and whereinpivoting of the left integrated hydraulic drive unit about the leftpivot axis comprises the left hydraulic pump, the left hydraulic motorand the left drive axle pivoting together as a unit about the left pivotaxis.
 5. The system of claim 1, further comprising: a right pivot rod,wherein the right integrated hydraulic drive unit is pivotally coupledto the frame by way of the right pivot rod; and a left pivot rod,wherein the left integrated hydraulic drive unit is pivotally coupled tothe frame by way of the left pivot rod.
 6. The system of claim 5,wherein the right pivot rod is coupled to a right member extending froma body of the frame, and wherein the left pivot rod is coupled to a leftmember extending from the body of the frame.
 7. The system of claim 5,further comprising: a right intermediate member, wherein the rightintegrated hydraulic drive unit is coupled to the right pivot rod by wayof the right intermediate member; and a left intermediate member,wherein the left integrated hydraulic drive unit is coupled to the leftpivot rod by way of the left intermediate member.
 8. The system of claim1, further comprising: a right pivot assembly, wherein the rightintegrated hydraulic drive unit is pivotally coupled to the frame by wayof the right pivot assembly, the right pivot assembly comprising: afirst right pivot element coupled to a first side of the rightintegrated hydraulic drive unit; and a second right pivot elementcoupled to a second side of the right integrated hydraulic drive unitand oriented coaxial with the first right pivot element; and a leftpivot assembly, wherein the left integrated hydraulic drive unit ispivotally coupled to the frame by way of the left pivot assembly, theleft pivot assembly comprising: a first left pivot element coupled to afirst side of the left integrated hydraulic drive unit; and a secondleft pivot element coupled to a second side of the left integratedhydraulic drive unit and oriented coaxial with the first left pivotelement.
 9. The system of claim 1, wherein the right resilient member isconfigured to be compressed by pivoting of the right integratedhydraulic drive unit in a first direction about the right pivot axis,wherein the left resilient member is configured to be compressed bypivoting of the left integrated hydraulic drive unit in a seconddirection about the left pivot axis, and wherein the second direction isopposite the first direction.
 10. The system of claim 1, wherein theright rear drive system further comprises a second right resilientmember configured to be compressed by pivoting of the right integratedhydraulic drive unit about the right pivot axis, and wherein the leftrear drive system further comprises a second left resilient memberconfigured to be compressed by pivoting of the left integrated hydraulicdrive unit about the left pivot axis.
 11. The system of claim 10,wherein the right resilient member and the second right resilient memberare located on opposite sides of the right axle axis from one another,and wherein the left resilient member and the second left resilientmember are located on opposite sides of the left axle axis from oneanother.
 12. The system of claim 1, wherein the riding lawnmower systemcomprises a zero-turn riding lawn mower.
 13. The system of claim 12,wherein the zero-turn riding lawn mower comprises a right steering armand a left steering arm, and wherein the right integrated hydraulicdrive unit is configured to transmit motive power to rotate the rightdrive axle and the right rear drive wheel responsive to manipulation ofthe right steering arm and the left integrated hydraulic drive unit isconfigured to transmit motive power to rotate the left drive axle andthe left rear drive wheel responsive to manipulation of the leftsteering arm.
 14. The system of claim 1, wherein the right integratedhydraulic drive unit comprises an integrated hydraulic transaxle, andwherein the left integrated hydraulic drive unit comprises an integratedhydraulic transaxle.
 15. A riding lawnmower system comprising: a frame;a right rear drive system comprising: a right integrated hydraulic driveunit comprising a right hydraulic pump, a right hydraulic motor and aright drive axle, the right drive axle configured to couple to a rightrear drive wheel and configured to rotate about a right axle axis, andthe right integrated hydraulic drive unit pivotally coupled to the framesuch that the right integrated hydraulic drive unit is configured topivot about a right pivot axis oriented transverse to the right axleaxis; and a right resilient member configured to be compressed bypivoting of the right integrated hydraulic drive unit about the rightpivot axis; and a left rear drive system comprising: a left integratedhydraulic drive unit comprising a left hydraulic pump, a left hydraulicmotor and a left drive axle, the left drive axle configured to couple toa left rear drive wheel and configured to rotate about a left axle axis,and the left integrated hydraulic drive unit pivotally coupled to theframe such that the left integrated hydraulic drive unit is configuredto pivot about a left pivot axis oriented transverse to the left axleaxis, the left integrated hydraulic drive unit is separate from theright integrated hydraulic drive unit, the right integrated hydraulicdrive unit is configured to pivot about the right pivot axis independentof pivoting of the left integrated hydraulic drive unit about the leftpivot axis, and the left integrated hydraulic drive unit is configuredto pivot about the left pivot axis independent of pivoting of the rightintegrated hydraulic drive unit about the right pivot axis; and a leftresilient member configured to be compressed by pivoting of the leftintegrated hydraulic drive unit about the left pivot axis.
 16. A ridinglawnmower system comprising: a frame; a right rear drive systemcomprising: a right integrated hydraulic drive unit comprising a rightdrive axle, the right drive axle configured to couple to a right reardrive wheel and configured to rotate about a right axle axis, and theright integrated hydraulic drive unit pivotally coupled to the framesuch that the right integrated hydraulic drive unit is configured topivot about a right pivot axis oriented transverse to the right axleaxis; and a right resilient member configured to be compressed bypivoting of the right integrated hydraulic drive unit about the rightpivot axis; and a left rear drive system comprising: a left integratedhydraulic drive unit comprising a left drive axle, the left drive axleconfigured to couple to a left rear drive wheel and configured to rotateabout a left axle axis, the left integrated hydraulic drive unitpivotally coupled to the frame such that the left integrated hydraulicdrive unit is configured to pivot about a left pivot axis orientedtransverse to the left axle axis, the left integrated hydraulic driveunit is separate from the right integrated hydraulic drive unit, theright integrated hydraulic drive unit is configured to pivot about theright pivot axis independent of pivoting of the left integratedhydraulic drive unit about the left pivot axis, and the left integratedhydraulic drive unit is configured to pivot about the left pivot axisindependent of pivoting of the right integrated hydraulic drive unitabout the right pivot axis; and a left resilient member configured to becompressed by pivoting of the left integrated hydraulic drive unit aboutthe left pivot axis.
 17. The system of claim 16, wherein the right axleaxis is oriented transverse to a longitudinal axis of the ridinglawnmower system, and the right pivot axis is offset to a right side ofthe longitudinal axis of the riding lawnmower system, and wherein theleft axle axis is oriented transverse to the longitudinal axis of theriding lawnmower system, and the left pivot axis is offset to a leftside of the longitudinal axis of the riding lawnmower system.
 18. Thesystem of claim 16, wherein the right integrated hydraulic drive unit isconfigured to transmit motive power to rotate the right drive axle aboutthe right axle axis, and wherein the left integrated hydraulic driveunit is configured to transmit motive power to rotate the left driveaxle about the left axle axis.
 19. The system of claim 16, wherein theright integrated hydraulic drive unit comprises a right hydraulic pump,a right hydraulic motor and the right drive axle, wherein pivoting ofthe right integrated hydraulic drive unit about the right pivot axiscomprises the right hydraulic pump, the right hydraulic motor and theright drive axle pivoting together as a unit about the right pivot axis,and wherein the left integrated hydraulic drive unit comprises a lefthydraulic pump, a left hydraulic motor and the left drive axle, andwherein pivoting of the left integrated hydraulic drive unit about theleft pivot axis comprises the left hydraulic pump, the left hydraulicmotor and the left drive axle pivoting together as a unit about the leftpivot axis.
 20. The system of claim 16, further comprising: a rightpivot rod, wherein the right integrated hydraulic drive unit ispivotally coupled to the frame by way of the right pivot rod; and a leftpivot rod, wherein the left integrated hydraulic drive unit is pivotallycoupled to the frame by way of the left pivot rod.
 21. The system ofclaim 20, wherein the right pivot rod is coupled to a right memberextending from a body of the frame, and wherein the left pivot rod iscoupled to a left member extending from the body of the frame.
 22. Thesystem of claim 20, further comprising: a right intermediate member,wherein the right integrated hydraulic drive unit is coupled to theright pivot rod by way of the right intermediate member; and a leftintermediate member, wherein the left integrated hydraulic drive unit iscoupled to the left pivot rod by way of the left intermediate member.23. The system of claim 16, further comprising: a right pivot assembly,wherein the right integrated hydraulic drive unit is pivotally coupledto the frame by way of the right pivot assembly, the right pivotassembly comprising: a first right pivot element coupled to a first sideof the right integrated hydraulic drive unit; and a second right pivotelement coupled to a second side of the right integrated hydraulic driveunit and oriented coaxial with the first right pivot element; and a leftpivot assembly, wherein the left integrated hydraulic drive unit ispivotally coupled to the frame by way of the left pivot assembly, theleft pivot assembly comprising: a first left pivot element coupled to afirst side of the left integrated hydraulic drive unit; and a secondleft pivot element coupled to a second side of the left integratedhydraulic drive unit and oriented coaxial with the first left pivotelement.
 24. The system of claim 16, wherein the right resilient memberis configured to be compressed by pivoting of the right integratedhydraulic drive unit in a first direction about the right pivot axis,wherein the left resilient member is configured to be compressed bypivoting of the left integrated hydraulic drive unit in a seconddirection about the left pivot axis, and wherein the second direction isopposite the first direction.
 25. The system of claim 16, wherein theright rear drive system further comprises a second right resilientmember configured to be compressed by pivoting of the right integratedhydraulic drive unit about the right pivot axis, and wherein the leftrear drive system further comprises a second left resilient memberconfigured to be compressed by pivoting of the left integrated hydraulicdrive unit about the left pivot axis.
 26. The system of claim 25,wherein the right resilient member and the second right resilient memberare located on opposite sides of the right axle axis from one another,and wherein the left resilient member and the second left resilientmember are located on opposite sides of the left axle axis from oneanother.
 27. The system of claim 16, wherein the riding lawnmower systemcomprises a zero-turn riding lawn mower comprising a right steering armand a left steering arm, and wherein the right integrated hydraulicdrive unit is configured to transmit motive power to rotate the rightdrive axle responsive to manipulation of the right steering arm and theleft integrated hydraulic drive unit is configured to transmit motivepower to rotate the left drive axle responsive to manipulation of theleft steering arm.
 28. The system of claim 16, wherein the rightintegrated hydraulic drive unit comprises an integrated hydraulictransaxle, and wherein the left integrated hydraulic drive unitcomprises an integrated hydraulic transaxle.